Technetium-99m labelled amine-functionalized polystyrene microplastics: An innovative approach for environmental and biological studies

The global issue of pollution has persisted for decades, with microplastics emerging as one of the most critical contaminants. Beyond their direct environmental impact, microplastics have recently been detected within living organisms, raising significant health and ecological concerns. Accurate tracing approaches are crucial for assessing these impacts and developing effective mitigation strategies. Among various techniques, radiolabelling offers distinct advantages due to its ability to track specific particles with high sensitivity, spatial precision, and allowing detection deep within biological tissue. In this study, commercially available amino-functionalized polystyrene (PS) microplastics were successfully radiolabelled using technetium-99m (Tc) to produce [Tc]Tc-NH-PS, achieving a labelling efficiency of 96.0 ± 1.5%. The radiolabelled microplastics exhibited strong in-vitro stability over 24 h, with stability exceeding 94% in fish Ringer's solution and simulated seawater, while lower stability (∼83-86%) was observed in simulated gastric fluid. Finally, neither the Z-average hydrodynamic diameter nor zeta potential significantly changed during radiolabeling, indicating Tc acts as a faithful tracer and did not induce particle degradation, aggregation, cross-linking, or changes in surface charge density. These results demonstrate that [Tc]Tc-NH-PS provides a practical, sensitive and versatile radiotracer platform for quantitative tracking of microplastics in environmental and biological systems.